The present invention relates to devices for securing objects onto supports, such as "blind" metal sheets, i.e. sheets accessible from only one side and perforated with appropriate holes through which the devices in question partially pass. Such devices are frequently required in the field of bodywork for road, rail, airborne vehicles or the like in addition to the domestic art or metal furniture field.
The present invention relates more particularly, among the fixing devices of the kind in question, to those devices which comprise a one-piece cage containing at least a partially threaded part which threadingly cooperates with a complementary threaded part to provide the desired securing functions. The cage includes a socket, a cylindrical or prismatic section small enough to be introduced into the fitting holes of the metal sheet or similar support. One of the ends of the socket is extended transversely with a collar adapted for bearing on the edges of the holes when the socket is introduced therein.
Known securing devices of this type present a number of advantages. In general, however, such known devices require complicated shapes for the fitting holes, each hole having the shape of an elongated slit with parallel edges or else that of a circle having notches radially outwardly extending therefrom.
One object, among others, of the present invention is to alleviate this requirement of such known devices by providing square-shaped holes for the securing devices.
In accordance with the present invention, the securing devices include a threaded part which comprises four identical radial tabs extending in two directions diametrically perpendicular with respect to one another and having a profile which is such that the cross thus defined may be introduced with very little clearance into the square holes.
Furthermore, the socket forming the cage thereof has a transverse section inscribable in a regular octagon and is itself adapted to being introduced with a slight clearance into the square holes. The socket is cut away so as to form four identical longitudinal windows offset angularly by 90 degrees with respect to one another. Each of the longitudinal windows is adapted to jointingly receive one of the four tabs of the threaded part. Means are also provided for enabling the threaded part to rotate through 45.degree. in the direction in which the complementary threaded part is threaded thereon between the time when the threaded part is introduced into a respective square hole and at least the end of the threading interengagement of the complementary threaded part with the partially threaded part.
In preferred embodiments, one or more of the following structural arrangements can be advantageously utilized.
Furthermore, when a socket has the general shape of a prism with an octagonal base, the means for enabling the threaded part to rotate through 45.degree. may include thinned-down portions provided in only one of the two halves of each of the four non-cutout portions of the lateral wall of the socket.
In another embodiment, when the socket has the general shape of a prism with an octagonal base, the means for enabling the threaded part to rotate through 45.degree. may include rounded cylindrical areas centered on the axis of the socket on the outer face of the non-cutout lateral wall portions thereof. Such areas preferably extend over half of each of those portions when viewed from a peripheral direction.
The means for enabling the threaded part to rotate through 45.degree. may also include oblique ribs provided on the outer faces of the non-cutout portions of the side wall of the socket. Such ribs are adapted to cooperate with the edges of the square holes so as to drive the socket angularly during its axial introduction into such a hole and to cause it to be automatically oriented at an angle of 45.degree. during this introduction.
Still a further embodiment contemplates that the means for enabling the threaded part to rotate through 45.degree. may be formed by the inclined shape given to the four windows cut out in the socket so that when the tabs of the threaded part slide along these windows subsequent to the threading engagement of the complementary threaded part thereon, the threaded part is oriented at an angle of 45.degree..
The collar preferably comprises at least two elastically flexible wings bent on the side of the socket and adapted to resiliently bear against the metal sheet in which the square hole is provided. The cage preferably comprises two flat bosses, triangular in cross-section, which axially project under the collar. Each boss is adapted to be jointingly introduced in two opposite corners of the square hole after the threaded part and the cage which contains it have rotated through 45.degree. subsequent to their common axial introduction thereinto.
The invention comprises, in addition to those features noted above, certain other features which are preferably used at the same time and which will be more explicitly discussed hereafter.